save the Blue Tier

natural history: liverworts

Random image of Blue Tier liverworts

According to the Checklist of Australian Liverworts
and Hornworts Tasmania had 416 out of the 871 species recorded
for the country at April 2006. We are not aware that anyone has made a
study of how many of these grow on the Blue Tier so it will be an
interesting exercise to start a record for liverworts.

The most familiar liverworts are the thallose forms of
which Marchantia species would be typical. However the most
common form to be found on the Blue Tier would be the leafy forms
which, from a distance, closely resemble some mosses. Usually a hand
lens is required to pick out the distinguishing features - the smaller
species require closer examination under a dissecting microscope. If
the stem has 2 rows of leaves on the surface and possibly another set
on the underside, and the leaves lack a midvein, it is likely to be a
leafy liverwort. However there are exceptions which make it difficult
for a novice to identify the specimen with any certitude. This is
nothing to be ashamed of since even taxonomists have been known (quite
reasonably) to misidentify mosses for liverworts
(Takakia lepidozioides).

Some of the leafy liverworts we have encountered are so tiny that
we could not have set out to discover them deliberately - they have
been found enmeshed with other more robust specimens we had
examined. The scales provided on the images and inserts are believed
to be reasonably accurate but these are not of much use in
identification as the same batch of plants may yield specimens that
vary in size by an order of magnitude.

The presence or absence of a third set of leaves (underleaves), as
well as their shape and arrangement along the stem, substrate and
growth habit are essential for keying out the species. The inserts
accompanying the main images provide details of these (underleaves
carry the notation 'U'). Some of these inserts are less than stellar
but provide what we consider the distinguishing features - we expect
to replace them with clearer images in time to come.

While a mature Eucalyptus regnans is an awesome sight we
suggest that the almost invisible macro-flora is no less a fascinating
subject. We recommend Meagher & Fuhrer's book mentioned below for
an introduction to mosses and liverworts, and suggest use of the
University of Tasmania key linked below to acquire some familiarity
with the subject.

On the left we have an image of a Chiloscyphus latifolius
sporophyte - unlike the persistent moss sporophytes these usually have
a short life span of a few hours within which to open and disperse
the spores, as depicted for Fossombronia on right [click
on thumbnail for larger image]. The helical objects in the images
are spring-like
'elaters' which
are believed to play a part in dispersal of spores.

In an ideal world every organism could be identified, or at least
be identifiable; in the inperfect world we inhabit some of the more
obscure forms do not easily fit into one category or another. The root
of the problem 'goes back a century or more when numerous species
were defined with great abandon, often based on limited examination of
specimens and with rather poor published descriptions'.

Notes:
'*' denotes specimen was collect outside the Blue Tier
'?' denotes some uncertainity in keying out specimens1Reported to differ from the NZ species

Literature:
- Scott, G.A.M., Southern Australian Liverworts,
Australian Flora and Fauna Series #2, 1986 (ISBN 064403632X) is the
classic work on Australian liverworts but is now out of print
- Meagher, D, & Fuhrer,
B., A
Field Guide to the Mosses and Allied Plants of Southern
Australia, (ISBN 0 642 56828 6), Flora of Australia
Supplementary Series, Number 20 - Australian Biological Resources
Study/The Field Naturalists Club of Victoria, 2003
- Meagher, D. 'Studies on Victorian bryophytes 5. Key to leafy
liverworts' and 'Studies on Victorian Bryophytes 6. Key to thallose
liverworts and hornworts', both appearing in Victorian
Naturalist Vol. 123(4) August 2006 pp 236-254 would find wide
application in Tasmania
- Glenny, D. & Malcolm, B., Key
to Australasian Liverwort and Hornwort Genera (ISBN 0 642
56840 5), Australian Biological Resources Study on CDRom is an
interactive key to 181 genera of liverworts and hornworts.
- In the absence of up-todate comprehensive treatment on Australian
liverworts we recommend the first of a series on NZ: Engel,
J.J. & Glenny, D., A Flora of the Liverworts and Hornworts
of New Zealand: Volume 1, ISBN
1930723679; Landcare
Research has made the contents of the entire volume online